Cosmarium panamense var. therezienii, Costa & Ramos & Moura, 2023

Costa, Fabiana De Matos, Ramos, Geraldo José Peixoto & Moura, Carlos Wallace Do Nascimento, 2023, New taxa of Cosmarium and Euastrum (Zygnematophyceae) from the North Coast of Bahia, Brazil, Phytotaxa 632 (2), pp. 193-200 : 197

Cosmarium panamense var. therezienii F.M. Costa, G.J.P.Ramos & C.W.N.Moura var. nov. ( Figs. 4 , 19–23 )

Diagnosis: —Cells slightly longer than broad, median constriction deep, sinus closed, linear; semicells trapeziform, margins crenate; cell wall covered by rows of granules surrounded by scrobicules; cell in apical view broadly ellipsoid. Cell dimensions: length 64–78.3 μm, breadth 56.3–60 μm, breadth of isthmus 20.4–23.5 μm.

Holotype:— Material numbered ( HUEFS 263034 !) [pro parte], deposited at the Herbarium of State University of Feira de Santana, population partially illustrated here ( Figs. 4 , 19–23 ).

Paratypes:— Material numbered ( HUEFS 263041) [pro parte], deposited at the Herbarium of State University of Feira de Santana.

Type locality:— BRAZIL. Bahia: Camaçari, Capivara Grande River, Lat. 12°45’05.8’’ S, Long. 38°10’22.4’’ W, 17 September 2019, F. M. Costa & M. S. Correia s/n ( HUEFS 263034).

Habitat:— Periphytic on Eleocharis acutangula ; water conductivity 0.08 mS.cm-1 (± 0.01); dissolved oxygen 8.0 mg.L-1 (± 1.3); pH 6.4 (± 0.5); total dissolved solids 0.04 ppt (± 0.01); water temperature 30 ºC (± 1.8).

Etymology:— The epithet is given in honor of the French desmidiologist Yves Thérézien for his contribution to knowledge of desmids, especially in South America.

Differential diagnosis:— Cosmarium panamense was proposed by Prescott (1936: 504), based on material collected in Panamá. In Brazil, this species is rarely reported in the literature. There is only a confirmed record of its occurrence in the Brazilian territory, which was based on the sample gathered in municipality of Andaraí, Bahia State ( Ramos et al. 2021). Thus, the material from the Capivara River basin represents the second taxonomic record of that species in Brazil.

Morphologically, the main characteristic that differs in C. panamense var. therezienii from the nominate variety is the cell outline, with trapeziform semicells in frontal view, and broadly ellipsoid in apical view. This morphotype is quite similar to the taxon described by Thérézien (1985: 108, PI. XXVIII - Fig. 2 ) from French Guiana.

Cosmarium panamense var. therezienii shows some morphological characteristics similar to C. decoratum West & G.S. West (1895: 61) , but the latter differs by having scrobicules with a triangular shape on the faces of the semicells, as illustrated by West & G.S. West (1895: pl.7, fig.21) and by Couté & Tell (1981: pl.10, fig.1-6).

Figures

FIGURES 2–5. Line drawings. 2. Cosmarium lineatum sp. nov. 3. C. margigranulatum sp. nov. 4. C. panamense var. therezienii var. nov. 5. Euastrum evolutum var. truncatum var. nov. Scale Bar: 10 μm.

FIGURES 19–28. Cosmarium panamense var. therezienii var. nov. (19–23): LM (20–23), SEM (19), frontal view (20–21), lateral view (22), apical view (23). Euastrum evolutum var. truncatum var. nov. (24–28): LM (25–26), SEM (24), frontal view (25–26), lateral view (27), apical view (28). Scale Bar: 10 μm.